The goal of this K01 Award application is to enhance the academic and scientific development of the Candidate, Dr. Falk. Under the guidance of Drs. Barry Byrne, Lucia Notterpek, David Fuller, and Scott Rivkees, the Candidate will pursue the link between respiratory insufficiency and the pathologic adaptations of axons, the neuromuscular junction, and skeletal muscle in Pompe disease. Pompe disease is a progressive disorder in which the deficiency or absence of acid alpha-glucosidase (GAA), leads to severe muscle weakness and often-premature death from respiratory muscle failure. The only FDA approved treatment for Pompe disease is enzyme replacement therapy (ERT). While ERT has improved outcomes, patients still suffer from inadequate alveolar ventilation and eventually require ventilatory assistance. Our long-term goal is to determine the mechanisms, which lead to respiratory muscle failure in this patient population. To make a significant shift in the management of care for Pompe patients, we have developed a systematic approach to identify the key mechanisms, which directly impact skeletal muscle activation and regulation. This will be accomplished using transgenic models of Pompe disease and recombinant adeno-associated virus (AAV) vectors. Recently, we observed that abrupt morphologic changes occur at the neuromuscular junction and may be key in elucidating the primary mechanism behind respiratory dysfunction. This application will focus on the role of the neuromuscular junction (NMJ) and potential therapies to restore skeletal muscle activation and function in Pompe disease. We will accomplish this by: 1) determining the negative impact at the neuromuscular junction as a result of CNS and skeletal muscle glycogen accumulation, 2) we will determine if skeletal muscle force production is primarily impaired due to pathologic adaptations in neurons and the neuromuscular junction in Pompe mice, and 3) directly compare existing and novel therapies to reduce glycogen deposition in critical tissues and ultimately restore respiratory and locomotor function in Pompe patients. In this regard, the specific aims seek to address several potential mechanisms for improving our overall understanding of the pathogenesis of Pompe disease and provide a platform for future research and funding to initiate an independent career centered on neuromuscular disease.